Do not block painting for in-body CSS

third_party/WebKit/Source/core/dom/StyleEngine.cpp

Index: third_party/WebKit/Source/core/dom/StyleEngine.cpp
diff --git a/third_party/WebKit/Source/core/dom/StyleEngine.cpp b/third_party/WebKit/Source/core/dom/StyleEngine.cpp
index bf0ea0dc6fa95c8863be8c13b3be1fc163ad84f6..4efede4c161a5a90df485266a957449614b0f8af 100644
--- a/third_party/WebKit/Source/core/dom/StyleEngine.cpp
+++ b/third_party/WebKit/Source/core/dom/StyleEngine.cpp
@@ -131,19 +131,26 @@ void StyleEngine::injectAuthorSheet(StyleSheetContents* authorSheet)
     resolverChanged(AnalyzedStyleUpdate);
 }
 
-void StyleEngine::addPendingSheet()
+void StyleEngine::addPendingSheet(bool isBeforeBody)
 {
     m_pendingStylesheets++;
+    if (isBeforeBody)
+        m_pendingRenderBlockingStylesheets++;
 }
 
 // This method is called whenever a top-level stylesheet has finished loading.
-void StyleEngine::removePendingSheet(Node* styleSheetCandidateNode)
+void StyleEngine::removePendingSheet(Node* styleSheetCandidateNode, bool isBeforeBody)
 {
     DCHECK(styleSheetCandidateNode);
     TreeScope* treeScope = isStyleElement(*styleSheetCandidateNode) ? &styleSheetCandidateNode->treeScope() : m_document.get();
     if (styleSheetCandidateNode->inShadowIncludingDocument())
         markTreeScopeDirty(*treeScope);
 
+    if (isBeforeBody) {
+        DCHECK_GT(m_pendingRenderBlockingStylesheets, 0);
+        m_pendingRenderBlockingStylesheets--;
+    }
+
     // Make sure we knew this sheet was pending, and that our count isn't out of sync.
     DCHECK_GT(m_pendingStylesheets, 0);
 
@@ -508,11 +515,11 @@ static bool isCacheableForStyleElement(const StyleSheetContents& contents)
     return true;
 }
 
-CSSStyleSheet* StyleEngine::createSheet(Element* e, const String& text, TextPosition startPosition)
+CSSStyleSheet* StyleEngine::createSheet(Element* e, const String& text, TextPosition startPosition, bool isBeforeBody)
 {
     CSSStyleSheet* styleSheet = nullptr;
 
-    e->document().styleEngine().addPendingSheet();
+    e->document().styleEngine().addPendingSheet(isBeforeBody);
 
     AtomicString textContent(text);